In vitro studies have shown an inhibitory effect of
lithium salts on herpes simplex virus (HSV) replication by mechanisms that interfere with
viral DNA synthesis. Moreover, clinical studies have shown that oral
lithium carbonate and topical
lithium succinate can suppress genital HSV
infections in humans. We conducted a randomized, double-blind, placebo-controlled trial of oral
lithium carbonate in 11 healthy subjects age 28-65 years (mean +/- SD age 38 +/- 11 years) who had at least four recurrent HSV
infections in the year preceding the study. Six patients completed at least 5 months of
lithium therapy at a mean (+/-SD) average daily
lithium dose of 437 +/- 185 mg (range, 150-900 mg) and an average serum
lithium level of 0.56 +/- 0.20 mmol/L. Overall,
lithium treatment resulted in a consistent reduction in the mean number of episodes/month, the average duration of each episode, the total number of
infection days/month, and the maximum symptom severity. In contrast, treatment with placebo resulted in an increase in three out of the four severity measures. Although the comparisons between the treatment groups did not achieve statistical significance due to the limited sample size, there was a clear "trend" for a reduction in the total monthly duration of all HSV
infections with
lithium (p = 0.08).
Lithium treatment was well tolerated and produced no deleterious effects on renal or thyroid function. These observations lend support to prior observations of an
antiviral activity of
lithium, and suggest the possibility that oral
lithium may represent a safe prophylactic agent in patients with recurrent HSV
infections.